GB267575A - Improvements in and relating to radio-telegraphic direction finding and similar methods and arrangements - Google Patents

Abstract

267,575. Watt, R. A. W., and Robinson, J. Nov. 7, 1925. Directive signalling; thermionic amplifiers.- In order to eliminate the effect of quadrantal error, or other aberrations due to lack of symmetry in the receiving circuits of direction-finding installations, wherein the input voltages from a plurality of aerials are separately amplified, as for example in the type of apparatus described in Specification 252,263, means are provided in the amplifier circuits for varying the ratio and, if necessary, the phase-relation of the amplified voltages. For instance, a variable tapping A, A<1> on the plate resistances R, R<1> may be employed to reduce the overall amplification from one or other of the directional aerials without introducing any phase difference in the output voltages. Or a variable grid leak may be used to give a similar control. Or the variable capacity C, C<1> included between the grid and filament connections of the first valve amplifier may be made only a fractional part of the total aerial capacity. Alternatively variable impedances or absorption traps L<1>, C<1>, R', Fig. 2, may be coupled to the plate circuits of the amplifiers so as to compensate for any input irregularities. Any phase-differences so introduced are removed by means of a phase-shifting device S<1>, one primary winding of which is directly included in the output circuit of one amplifier, whilst the other primary winding forms part of a resonant circuit coupled to the output of the associated amplifier.